The Functional Capacity of X-Irradiated Macrophages

Graded doses of x-irradiation (up to 10,000 R) had no effect on the uptake and little effect on the catabolism of keyhole limpet hemocyanin (KLH) or human γ-globulin (HGG) in vitro by macrophages from non-immunized CBA or A mice. After uptake and catabolism, however, greater amounts of KLH and HGG remained associated with the plasma membrane of x-irradiated (10,000 R) macrophages compared with control cells. Because of their greater surface binding of antigens, x-irradiated macrophages after transfer to normal mice were more effective in inducing immune responses to antigens to which they were exposed in vitro than were normal macrophages. This increased immunogenicity of KLH bound to x-irradiated macrophages was abrogated by treating the cells with trypsin before transfer. In addition, transfer of normal macrophages carrying KLH or HGG to sublethally irradiated mice did not reconstitute their ability to form antibody to these proteins.